Multi-speed transmission with external drive gearsets

ABSTRACT

A transmission is provided having an input member, an output member, three planetary gear sets, four external gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. Each of the external gear sets includes first and second gears. The torque transmitting devices may include clutches and brakes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/974,222, filed on Sep. 21, 2007. The disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The invention relates generally to a multiple speed transmission havinga plurality of gear sets and a plurality of torque transmitting devices,and more particularly to a transmission having eight or more speedsproduced by a combination of planetary gear sets, external gear sets andtorque transmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of frictionclutches or brakes, planetary gear arrangements and fixedinterconnections to achieve a plurality of gear ratios. The number andphysical arrangement of the planetary gear sets, generally, are dictatedby packaging, cost and desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

A transmission is provided having an input member, an output member,three planetary gear sets, four external gear sets, a plurality ofcoupling members and a plurality of torque transmitting devices. Each ofthe planetary gear sets includes first, second and third members. Eachof the external gear sets include first and second gear members. Thetorque transmitting devices are for example clutches and brakes.

An embodiment of the transmission includes an input member, an outputmember, a first, second, and third planetary gear set each having afirst, second, and third member, a first, second, third, and fourth gearset each having a first gear intermeshed with a second gear, a firstinterconnecting member continuously interconnecting the second gear ofthe third gear set with the first member of the first planetary gearset, a second interconnecting member continuously interconnecting thesecond member of the first planetary gear set with the second member ofthe second planetary gear set, a third interconnecting membercontinuously interconnecting the first member of the second planetarygear set with the second gear of the first gear set, a fourthinterconnecting member continuously interconnecting the third member ofthe second planetary gear set with the first gear of the second gearset, a fifth interconnecting member continuously interconnecting thefirst member of the third planetary gear set with the first gear of thethird gear set, and a sixth interconnecting member continuouslyinterconnecting the second member of the third planetary gear set withthe first gear of the fourth gear set. Five torque transmittingmechanisms are selectively engageable to interconnect one of the firstmembers, second members, third members, first gears, and second gearswith at least one of the first members, second members, third members,first gears, second gears, and a stationary element. The torquetransmitting mechanisms are selectively engageable in combinations of atleast three to establish at least eight forward speed ratios and atleast one reverse speed ratio between the input member and the outputmember.

In one aspect of the present invention, a first of the five torquetransmitting mechanisms is selectively engageable to interconnect atleast one of the second member of the first planetary gear set and thesecond member of the second planetary gear set with at least one of thefirst member of the first planetary gear set and the second gear of thethird gear set.

In another aspect of the present invention, a second of the five torquetransmitting mechanisms is selectively engageable to interconnect atleast one of the third member of the second planetary gear set and thefirst gear of the second gear set with at least one of the first memberof the first planetary gear set and the second gear of the third gearset.

In yet another aspect of the present invention, a third of the fivetorque transmitting mechanisms is selectively engageable to interconnectthe third member of the third planetary gear set with the second gear ofthe second gear set.

In yet another aspect of the present invention, a fourth of the fivetorque transmitting mechanisms is selectively engageable to interconnectthe third member of the third planetary gear set with the first gear ofthe first gear set.

In yet another aspect of the present invention, a fifth of the fivetorque transmitting mechanisms is selectively engageable to interconnectat least one of the second gear of the first gear set and the firstmember of the second planetary gear set with the stationary element.

In yet another aspect of the present invention, the second and fourthinterconnecting members are sleeve shafts that are concentric with thefirst interconnecting member.

In yet another aspect of the present invention, the third torquetransmitting mechanism is connected to the second gear of the secondco-planar gear set by a first sleeve shaft and the fourth torquetransmitting mechanism is connected to the second gear of the secondco-planar gear set by a second sleeve shaft, and the first and secondsleeve shafts are concentric with the fifth interconnecting member.

In yet another aspect of the present invention, the input member iscontinuously interconnected with the third member of the first planetarygear set and the output member is continuously interconnected with thesecond gear of the fourth gear set.

In yet another aspect of the present invention, the first members aresun gears, the second members are carrier members, and the third membersare ring gears.

In yet another aspect of the present invention, the first gears and thesecond gears within each of the first, second, third, and fourth gearsets are co-planar.

In yet another aspect of the present invention, the fifth and sixthinterconnecting members are offset from the input member and the first,second, third, and fourth interconnecting members.

In yet another aspect of the present invention, the output member isoffset from the first, second, third, fourth, fifth, and sixthinterconnecting members and the input member.

In yet another aspect of the present invention, the stationary elementis a transmission housing.

Another embodiment of the transmission of the present invention includesan input member, an output member, a first, second, and third planetarygear set each having a first, second, and third member, wherein theinput member is continuously interconnected with the third member of thefirst planetary gear set, a first, second, third, and fourth gear seteach having a first gear intermeshed with a second gear, wherein theoutput member is continuously interconnected with the second gear of thefourth gear set, a first interconnecting member continuouslyinterconnecting the second gear of the third gear set with the firstmember of the first planetary gear set, a second interconnecting membercontinuously interconnecting the second member of the first planetarygear set with the second member of the second planetary gear set, athird interconnecting member continuously interconnecting the firstmember of the second planetary gear set with the second gear of thefirst gear set, a fourth interconnecting member continuouslyinterconnecting the third member of the second planetary gear set withthe first gear of the second gear set, a fifth interconnecting membercontinuously interconnecting the first member of the third planetarygear set with the first gear of the third gear set, and a sixthinterconnecting member continuously interconnecting the second member ofthe third planetary gear set with the first gear of the fourth gear set.A first torque transmitting mechanism is selectively engageable tointerconnect at least one of the second member of the first planetarygear set and the second member of the second planetary gear set with atleast one of the first member of the first planetary gear set and thesecond gear of the third gear set, a second torque transmittingmechanism is selectively engageable to interconnect at least one of thethird member of the second planetary gear set and the first gear of thesecond gear set with at least one of the first member of the firstplanetary gear set and the second gear of the third gear set, a thirdtorque transmitting mechanism is selectively engageable to interconnectthe third member of the third planetary gear set with the second gear ofthe second gear set, a fourth torque transmitting mechanism isselectively engageable to interconnect the third member of the thirdplanetary gear set with the first gear of the first gear set, and afifth torque transmitting mechanism is selectively engageable tointerconnect at least one of the second gear of the first gear set andthe first member of the second planetary gear set with a stationaryelement. The torque transmitting mechanisms are selectively engageablein combinations of at least three to establish at least eight forwardspeed ratios and at least one reverse speed ratio between the inputmember and the output member.

In one aspect of the present invention, the first members are sun gears,the second members are carrier members, and the third members are ringgears.

In another aspect of the present invention, the first gears and thesecond gears within each of the first, second, third, and fourth gearsets are co-planar.

In yet another aspect of the present invention, the fifth and sixthinterconnecting members are offset from the input member and the first,second, third, and fourth interconnecting members.

In yet another aspect of the present invention, the output member isoffset from the first, second, third, fourth, fifth, and sixthinterconnecting members and the input member.

In yet another aspect of the present invention, the stationary elementis a transmission housing.

Still another embodiment of the transmission of the present inventionincludes an input member, an output member, a first, second, and thirdplanetary gear set each having a sun gear, a carrier member, and a ringgear, wherein the input member is continuously interconnected with thering gear of the first planetary gear set, a first, second, third, andfourth gear set each having a first gear intermeshed with a second gear,wherein the output member is continuously interconnected with the secondgear of the fourth gear set, a first interconnecting member continuouslyinterconnecting the second gear of the third gear set with the sun gearof the first planetary gear set, a second interconnecting membercontinuously interconnecting the carrier member of the first planetarygear set with the carrier member of the second planetary gear set, athird interconnecting member continuously interconnecting the sun gearof the second planetary gear set with the second gear of the first gearset, a fourth interconnecting member continuously interconnecting thering gear of the second planetary gear set with the first gear of thesecond gear set, a fifth interconnecting member continuouslyinterconnecting the sun gear of the third planetary gear set with thefirst gear of the third gear set, and a sixth interconnecting membercontinuously interconnecting the carrier member of the third planetarygear set with the first gear of the fourth gear set. A first torquetransmitting mechanism is selectively engageable to interconnect atleast one of the carrier member of the first planetary gear set and thecarrier member of the second planetary gear set with at least one of thesun gear of the first planetary gear set and the second gear of thethird gear set, a second torque transmitting mechanism is selectivelyengageable to interconnect at least one of the ring gear of the secondplanetary gear set and the first gear of the second gear set with atleast one of the sun gear of the first planetary gear set and the secondgear of the third gear set, a third torque transmitting mechanism isselectively engageable to interconnect the ring gear of the thirdplanetary gear set with the second gear of the second gear set, a fourthtorque transmitting mechanism is selectively engageable to interconnectthe ring gear of the third planetary gear set with the first gear of thefirst gear set, and a fifth torque transmitting mechanism is selectivelyengageable to interconnect at least one of the second gear of the firstgear set and the sun gear of the second planetary gear set with astationary element. The torque transmitting mechanisms are selectivelyengageable in combinations of at least three to establish at least eightforward speed ratios and at least one reverse speed ratio between theinput member and the output member.

In one aspect of the present invention, the first gears and the secondgears within each of the first, second, third, and fourth gear sets areco-planar.

In another aspect of the present invention, the fifth and sixthinterconnecting members are offset from the input member and the first,second, third, and fourth interconnecting members.

In yet another aspect of the present invention, the output member isoffset from the first, second, third, fourth, fifth, and sixthinterconnecting members and the input member.

In yet another aspect of the present invention, the stationary elementis a transmission housing.

Further objects, aspects and advantages of the present invention willbecome apparent by reference to the following description and appendeddrawings wherein like reference numbers refer to the same component,element or feature.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a lever diagram of an embodiment of an eight speedtransmission according to the present invention;

FIG. 2 is a diagrammatic view of an embodiment of an eight speedtransmission according to the present invention; and

FIG. 3 is a truth table presenting the state of engagement of thevarious torque transmitting elements in each of the available forwardand reverse speeds or gear ratios of the transmission illustrated inFIGS. 1 and 2.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

Referring now to FIG. 1, an embodiment of an eight speed transmission 10is illustrated in a lever diagram format. A lever diagram is a schematicrepresentation of the components of a mechanical device such as anautomatic transmission. Each individual lever represents a gear set.Solid line levers represent a planetary gear set wherein the three basicmechanical components of the planetary gear set are each represented bya node. Therefore, a single planetary gear set lever contains threenodes: one for the sun gear, one for the planet gear carrier, and onefor the ring gear. Dashed line levers are spur or external drive gearsets which may be represented in the lever diagram as planetary gearsets having grounded planet carrier members. Accordingly, the outernodes represent the first and second drive gears and the inner noderepresents the imaginary grounded planet carrier member. The relativelength between the nodes of each lever can be used to represent thering-to-sun ratio and first drive gear to second drive gear ratio ofeach respective gear set. These lever ratios, in turn, are used to varythe gear ratios of the transmission in order to achieve appropriateratios and ratio progression. Mechanical couplings or interconnectionsbetween the nodes of the various planetary gear sets are illustrated bythin, horizontal lines and torque transmitting devices such as clutchesand brakes are presented as interleaved fingers. Where the torquetransmitting device is a brake, one set of interleaved fingers iscoupled to a ground. Further explanation of the format, purpose and useof lever diagrams can be found in SAE Paper 810102, “The Lever Analogy:A New Tool in Transmission Analysis” by Benford and Leising which ishereby fully incorporated by reference.

The transmission 10 includes an input shaft or member 12, a firstplanetary gear set 14 having three nodes: a first node 14A, a secondnode 14B and a third node 14C, a second planetary gear set 16 havingthree nodes: a first node 16A, a second node 16B and a third node 16C, athird planetary gear set 18 having three nodes: a first node 18A, asecond node 18B and a third node 18C, a first external gear set 20having three nodes: a first node 20A, a second node 20B and a third node20C, a second external gear set 22 having three nodes: a first node 22A,a second node 22B and a third node 22C, a second external gear set 24having three nodes: a first node 24A, a second node 24B and a third node24C, a fourth external gear set 26 having three nodes: a first node 26A,a second node 26B and a third node 26C, and an output shaft or member30.

The input member 12 is coupled to the third node 14C of the firstplanetary gear set 14. The output member 30 is coupled to the third node26C of the fourth external gear set 26. The first node 14A of the firstplanetary gear set 14 is coupled to the third node 24C of the thirdexternal gear set 24. The second node 14B of the first planetary gearset 14 is coupled to the second node 16B of the second planetary gearset 16. The first node 16A of the second planetary gear set 16 iscoupled to the first node 22A of the second external gear set 22. Thethird node 16C of the second planetary gear set 16 is coupled to thethird node 20C of the first external gear set 20. The first node 18A ofthe third planetary gear set 18 is coupled to the first node 24A of thethird external gear set 24. The second node 18B of the third planetarygear set 18 is coupled to the first node 26A of the fourth external gearset 26.

A first clutch 40 selectively connects the second node 14B of the firstplanetary gear set 14 to the third node 24C of the third external gearset 24. A second clutch 42 selectively connects first node 14A of thefirst planetary gear set 14 and the third node 24C of the third externalgear set 24 to the first node 16A of the second planetary gear set 16. Athird clutch 44 selectively connects the third node 22C of the secondexternal gear set 22 to the third node 18C of the third planetary gearset 18. A fourth clutch 46 selectively connects the third node 18C ofthe third planetary gear set 18 to the first node 20A of the firstexternal gear set 20. A brake 48 selectively connects the third node 16Cof the second planetary gear set 16 to a stationary element ortransmission housing 50.

Referring now to FIG. 2, a schematic diagram illustrates an embodimentof the eight speed transmission 10 according to the present invention.In FIG. 2, the numbering from the lever diagram of FIG. 1 is carriedover. The clutches, brakes, and couplings or interconnections arecorrespondingly presented whereas the nodes of the planetary gear setsnow appear as components of planetary gear sets such as sun gears, ringgears, planet gears and planet gear carriers and the nodes of theexternal drive gear sets now appear as components of the external drivegear sets such as first and second drive gears.

For example, planetary gear set 14 includes a sun gear member 14A, aplanet gear carrier member 14B and a ring gear member 14C. The planetgear carrier member 14B rotatably supports a set of planet gears 14Dconfigured to intermesh with both the sun gear member 14A and the ringgear member 14C. The sun gear member 14A is connected for commonrotation with a first shaft or interconnecting member 52. The planetcarrier member 14B is connected for common rotation with a second shaftor interconnecting member 54. The ring gear member 14C is connected forcommon rotation with the input shaft or member 12.

The planetary gear set 16 includes a sun gear member 16C, a planet gearcarrier member 16B and a ring gear member 16A. The planet gear carriermember 16B rotatably supports a set of planet gears 16D configured tointermesh with both the sun gear member 16C and the ring gear member16A. The sun gear member 16C is connected for common rotation with athird shaft or interconnecting member 56. The ring gear member 16A isconnected for common rotation with a fourth shaft or interconnectingmember 58. The planet carrier member 16B is connected for commonrotation with second shaft or interconnecting member 54.

The planetary gear set 18 includes a sun gear member 18A, a planet gearcarrier member 18B and a ring gear member 18C. The planet gear carriermember 18B rotatably supports a set of planet gears 18D configured tointermesh with both the sun gear member 18A and the ring gear member18C. The sun gear member 18A is connected for common rotation with afifth shaft or interconnecting member 60. The ring gear member 18C isconnected for common rotation with a sixth shaft or interconnectingmember 62. The planet carrier member 18B is connected for commonrotation with a seventh shaft or interconnecting member 64.

The external gear set 20 includes a first gear member 20A intermeshedwith a second gear member 20C. The first gear member 20A is connectedfor common rotation with an eighth interconnecting member 66. The secondgear member 20C is connected for common rotation with the third shaft orinterconnecting member 56.

The external gear set 22 includes a first gear member 22A intermeshedwith a second gear member 22C. The first gear member 22A is connectedfor common rotation with the fourth interconnecting member 58. Thesecond gear member 22C is connected for common rotation with a ninthinterconnecting member 68.

The external gear set 24 includes a first gear member 24A intermeshedwith a second gear member 24C. The first gear member 24A is connectedfor common rotation with the fifth interconnecting member 60. The secondgear member 24C is connected for common rotation with the first shaft orinterconnecting member 52.

The external gear set 26 includes a first gear member 26A intermeshedwith a second gear member 26C. The first gear member 26A is connectedfor common rotation with seventh interconnecting member 64. The secondgear member 26C is connected for common rotation with the output member30.

The input shaft or member 12 is continuously connected to an engine (notshown) or to a turbine of a torque converter (not shown). The outputshaft or member 30 is continuously connected with the final drive unitor transfer case (not shown).

The torque-transmitting elements or the clutches 40, 42, 44, 46 andbrake 48 allow for selective interconnection of the shafts orinterconnecting members, members of the planetary gear sets and externalgear sets, and the transmission housing. For example, the first clutch40 is selectively engageable to connect the first interconnecting member52 with the second interconnecting member 54. The second clutch 42 isselectively engageable to connect the first interconnecting member 52with the fourth interconnecting member 58. The third clutch 44 isselectively engageable to connect the sixth interconnecting member 62with the ninth interconnecting member 68. The fourth clutch 46 isselectively engageable to connect the sixth interconnecting member 62with the fifth interconnecting member 66. The brake 48 is selectivelyengageable to connect the first interconnecting member 56 to astationary element or the transmission housing 50 in order to restrictthe first interconnecting member 56 and therefore the third gear member20C and the sun gear member 16C from rotating relative to thetransmission housing 50.

In the particular example provided, the transmission 10 is arrangedalong three parallel and spaced apart axes including a first axisdefined by the input member 12 and first interconnecting member 52, asecond axis defined by the fifth interconnecting member 60, and a thirdaxis defined by the output member 30. Accordingly, in the exampleprovided, the interconnecting members 54, 56, 58, the planetary gearsets 14 and 16, the second gear member 20C, the first gear member 22A,the second gear member 24C, the brake 48 and the clutches 40, 42 are allcoaxial with the first axis. The interconnecting members 62, 66, 68, thesecond planetary gear set 18, the first gear member 20A, the second gearmember 22C, the first gear member 24A, the first gear member 26A, thethird clutch 44, the fourth clutch 46 and are all coaxial with thesecond axis. Finally, the second gear member 26C is coaxial with thethird axis. Additionally, the transmission 10 is preferably configuredfor a front wheel drive vehicle.

Referring now to FIG. 3, the operation of the embodiments of the eightspeed transmission 10 will be described. It will be appreciated that thetransmission 10 is capable of transmitting torque from the input shaftor member 12 to the output shaft or member 30 in at least eight forwardspeed or torque ratios and at least one reverse speed or torque ratio.Each forward and reverse speed or torque ratio is attained by engagementof one or more of the torque-transmitting mechanisms (i.e. first clutch40, second clutch 42, third clutch 44, fourth clutch 46, and brake 48),as will be explained below. FIG. 3 is a truth table presenting thevarious combinations of torque-transmitting mechanisms that areactivated or engaged to achieve the various gear states. Actualnumerical gear ratios of the various gear states are also presentedalthough it should be appreciated that these numerical values areexemplary only and that they may be adjusted over significant ranges toaccommodate various applications and operational criteria of thetransmission 10. An example of the gear ratios that may be obtainedusing the embodiments of the present invention are also shown in FIG. 3.Of course, other gear ratios are achievable depending on the geardiameter, gear teeth count and gear configuration selected.

To establish reverse gear, the third clutch 44, the fourth clutch 46,and the brake 48 are engaged or activated. The third clutch 44 connectsthe sixth interconnecting member 62 with the ninth interconnectingmember 68. The fourth clutch 46 connects the sixth interconnectingmember 62 with the eighth interconnecting member 66. The brake 48connects the third interconnecting member 56 to a stationary element orthe transmission housing 50 in order to restrict the thirdinterconnecting member 56 and therefore the second gear member 20C andthe sun gear member 16C from rotation relative to the transmissionhousing 50. Likewise, the eight forward ratios are achieved throughdifferent combinations of clutch and brake engagement, as shown in FIG.3.

It will be appreciated that the foregoing explanation of operation andgear states of the eight speed transmission 10 assumes, first of all,that all the clutches and brakes not specifically referenced in a givengear state are inactive or disengaged and, second of all, that duringgear shifts, i.e., changes of gear state, between at least adjacent gearstates, a clutch or brake engaged or activated in both gear states willremain engaged or activated.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; afirst, second, and third planetary gear set each having a first, second,and third member; a first, second, third, and fourth co-planar gear seteach having a first gear intermeshed with a second gear; a firstinterconnecting member continuously interconnecting the second gear ofthe third co-planar gear set with the first member of the firstplanetary gear set; a second interconnecting member continuouslyinterconnecting the second member of the first planetary gear set withthe second member of the second planetary gear set; a thirdinterconnecting member continuously interconnecting the first member ofthe second planetary gear set with the second gear of the firstco-planar gear set; a fourth interconnecting member continuouslyinterconnecting the third member of the second planetary gear set withthe first gear of the second co-planar gear set; a fifth interconnectingmember continuously interconnecting the first member of the thirdplanetary gear set with the first gear of the third co-planar gear set;a sixth interconnecting member continuously interconnecting the secondmember of the third planetary gear set with the first gear of the fourthco-planar gear set; and five torque transmitting mechanisms selectivelyengageable to interconnect one of the first members, second members,third members, first gears, and second gears with at least one of thefirst members, second members, third members, first gears, second gears,and a stationary element, and wherein the torque transmitting mechanismsare selectively engageable in combinations of at least three toestablish at least eight forward speed ratios and at least one reversespeed ratio between the input member and the output member.
 2. Thetransmission of claim 1 wherein a first of the five torque transmittingmechanisms is selectively engageable to interconnect at least one of thesecond member of the first planetary gear set and the second member ofthe second planetary gear set with at least one of the first member ofthe first planetary gear set and the second gear of the third co-planargear set.
 3. The transmission of claim 2 wherein a second of the fivetorque transmitting mechanisms is selectively engageable to interconnectat least one of the third member of the second planetary gear set andthe first gear of the second co-planar gear set with at least one of thefirst member of the first planetary gear set and the second gear of thethird co-planar gear set.
 4. The transmission of claim 3 wherein a thirdof the five torque transmitting mechanisms is selectively engageable tointerconnect the third member of the third planetary gear set with thesecond gear of the second co-planar gear set.
 5. The transmission ofclaim 4 wherein a fourth of the five torque transmitting mechanisms isselectively engageable to interconnect the third member of the thirdplanetary gear set with the first gear of the first co-planar gear set.6. The transmission of claim 5 wherein a fifth of the five torquetransmitting mechanisms is selectively engageable to interconnect atleast one of the second gear of the first co-planar gear set and thefirst member of the second planetary gear set with the stationaryelement.
 7. The transmission of claim 1 wherein the input member iscontinuously interconnected with the third member of the first planetarygear set and wherein the output member is continuously interconnectedwith the second gear of the fourth co-planar gear set.
 8. Thetransmission of claim 1 wherein the first members are sun gears, thesecond members are carrier members, and the third members are ringgears.
 9. The transmission of claim 1 wherein the second and fourthinterconnecting members are sleeve shafts that are concentric with thefirst interconnecting member.
 10. The transmission of claim 1 whereinthe fifth and sixth interconnecting members are offset from the inputmember and the first, second, third, and fourth interconnecting members,and wherein the output member is offset from the first, second, third,fourth, fifth, and sixth interconnecting members and the input member.11. The transmission of claim 6 wherein the third torque transmittingmechanism is connected to the second gear of the second co-planar gearset by a first sleeve shaft and the fourth torque transmitting mechanismis connected to the second gear of the second co-planar gear set by asecond sleeve shaft, wherein the first and second sleeve shafts areconcentric with the fifth interconnecting member.
 12. The transmissionof claim 1 wherein the stationary element is a transmission housing. 13.A transmission comprising: an input member; an output member; a first,second, and third planetary gear set each having a first, second, andthird member, wherein the input member is continuously interconnectedwith the third member of the first planetary gear set; a first, second,third, and fourth co-planar gear set each having a first gearintermeshed with a second gear, wherein the output member iscontinuously interconnected with the second gear of the fourth co-planargear set; a first interconnecting member continuously interconnectingthe second gear of the third co-planar gear set with the first member ofthe first planetary gear set; a second interconnecting membercontinuously interconnecting the second member of the first planetarygear set with the second member of the second planetary gear set; athird interconnecting member continuously interconnecting the firstmember of the second planetary gear set with the second gear of thefirst co-planar gear set; a fourth interconnecting member continuouslyinterconnecting the third member of the second planetary gear set withthe first gear of the second co-planar gear set; a fifth interconnectingmember continuously interconnecting the first member of the thirdplanetary gear set with the first gear of the third co-planar gear set;a sixth interconnecting member continuously interconnecting the secondmember of the third planetary gear set with the first gear of the fourthco-planar gear set; a first torque transmitting mechanism selectivelyengageable to interconnect at least one of the second member of thefirst planetary gear set and the second member of the second planetarygear set with at least one of the first member of the first planetarygear set and the second gear of the third co-planar gear set; a secondtorque transmitting mechanism selectively engageable to interconnect atleast one of the third member of the second planetary gear set and thefirst gear of the second co-planar gear set with at least one of thefirst member of the first planetary gear set and the second gear of thethird co-planar gear set; a third torque transmitting mechanismselectively engageable to interconnect the third member of the thirdplanetary gear set with the second gear of the second co-planar gearset; a fourth torque transmitting mechanism selectively engageable tointerconnect the third member of the third planetary gear set with thefirst gear of the first co-planar gear set; and a fifth torquetransmitting mechanism selectively engageable to interconnect at leastone of the second gear of the first co-planar gear set and the firstmember of the second planetary gear set with a stationary element, andwherein the torque transmitting mechanisms are selectively engageable incombinations of at least three to establish at least eight forward speedratios and at least one reverse speed ratio between the input member andthe output member.
 14. The transmission of claim 13 wherein the firstmembers are sun gears, the second members are carrier members, and thethird members are ring gears.
 15. The transmission of claim 13 whereinthe first gears and the second gears within each of the first, second,third, and fourth co-planar gear sets are co-planar.
 16. Thetransmission of claim 13 wherein the fifth and sixth interconnectingmembers are offset from the input member and the first, second, third,and fourth interconnecting members.
 17. The transmission of claim 13wherein the output member is offset from the first, second, third,fourth, fifth, and sixth interconnecting members and the input member.18. The transmission of claim 13 wherein the stationary element is atransmission housing.
 19. A transmission comprising: an input member; anoutput member; a first, second, and third planetary gear set each havinga sun gear, a carrier member, and a ring gear, wherein the input memberis continuously interconnected with the ring gear of the first planetarygear set; a first, second, third, and fourth co-planar gear set eachhaving a first gear intermeshed with a second gear, wherein the outputmember is continuously interconnected with the second gear of the fourthco-planar gear set; a first interconnecting member continuouslyinterconnecting the second gear of the third co-planar gear set with thesun gear of the first planetary gear set; a second interconnectingmember continuously interconnecting the carrier member of the firstplanetary gear set with the carrier member of the second planetary gearset; a third interconnecting member continuously interconnecting the sungear of the second planetary gear set with the second gear of the firstco-planar gear set; a fourth interconnecting member continuouslyinterconnecting the ring gear of the second planetary gear set with thefirst gear of the second co-planar gear set; a fifth interconnectingmember continuously interconnecting the sun gear of the third planetarygear set with the first gear of the third co-planar gear set; a sixthinterconnecting member continuously interconnecting the carrier memberof the third planetary gear set with the first gear of the fourthco-planar gear set; a first torque transmitting mechanism selectivelyengageable to interconnect at least one of the carrier member of thefirst planetary gear set and the carrier member of the second planetarygear set with at least one of the sun gear of the first planetary gearset and the second gear of the third co-planar gear set; a second torquetransmitting mechanism selectively engageable to interconnect at leastone of the ring gear of the second planetary gear set and the first gearof the second co-planar gear set with at least one of the sun gear ofthe first planetary gear set and the second gear of the third co-planargear set; a third torque transmitting mechanism selectively engageableto interconnect the ring gear of the third planetary gear set with thesecond gear of the second co-planar gear set; a fourth torquetransmitting mechanism selectively engageable to interconnect the ringgear of the third planetary gear set with the first gear of the firstco-planar gear set; and a fifth torque transmitting mechanismselectively engageable to interconnect at least one of the second gearof the first co-planar gear set and the sun gear of the second planetarygear set with a stationary element, and wherein the torque transmittingmechanisms are selectively engageable in combinations of at least threeto establish at least eight forward speed ratios and at least onereverse speed ratio between the input member and the output member. 20.The transmission of claim 19 wherein the first gears and the secondgears within each of the first, second, third, and fourth co-planar gearsets are co-planar.
 21. The transmission of claim 20 wherein fifth andsixth interconnecting members are offset from the input member and thefirst, second, third, and fourth interconnecting members.
 22. Thetransmission of claim 21 wherein the output member is offset from thefirst, second, third, fourth, fifth, and sixth interconnecting membersand the input member.
 23. The transmission of claim 22 wherein thestationary element is a transmission housing.